Observational, nonintervention, multicenter study for validation of the Bowel Function Index for constipation in European countries.

OBJECTIVE: Constipation is a common adverse event of treatment with opioids for chronic non-malignant pain and may result in a considerable reduction in health-related quality of life. The aim of this study was to assess the psychometric properties of the Bowel Function Index (BFI) in european patients suffering from constipation secondary to opioid analgesic treatment for chronic, non-malignant pain.

METHODS: This was a multinational study conducted at 15 clinical sites in the Czech Republic, Germany, Italy, and the United Kingdom. Patients suffering from constipation secondary to opioid analgesic treatment for chronic, non-malignant pain were recruited to complete a series of questionnaires including a socio-demographic form, the BFI, the Patient Assessment of Constipation - Symptoms (PAC-SYM), a global frequency item, and a clinical form.

RESULTS: A total of 131 patients were included in this study. Inter-item correlations of the BFI were statistically significant in the moderate to large range and the analysis indicated a strong degree of internal consistency (Cronbach's alpha = 0.86). All correlations between the BFI and the global item were statistically significant in the moderate to high range (r = 0.59 to 0.69; p < 0.0001). Correlations between the BFI and the PAC-SYM were moderate and statistically significant (p < 0.01 to 0.0001).

CONCLUSIONS: Although this study was limited by the relatively small sample size, it is a part of an extensive validation program. This study suggests that the BFI is a reliable and valid measure of constipation-related symptomatology in chronic pain patients. This measure may be a valuable indicator of patients' experience of symptoms of opioid treatment of chronic pain in future trials.